The present invention relates to a mounting structure for an electronic part, and in particular, it relates to a structure for mounting an electronic part such as a semiconductor package at an electrical connector such as a wiring formed on a substrate surface.
Inside an electronic device, an electrical circuit is constituted by mounting a number of different types of electronic parts on a surface of a substrate where various wirings are formed to achieve miniaturization of the electronic device and a higher density in the electronic device. It is to be noted that in this specification, the term "electronic part" refers to a part achieved through packaging various types of electronic elements that can be electrically operated, including integrated semiconductor elements such as various types of transistors and memories, circuit elements such as resistors and capacitors and optical elements such as light modulators, laser diodes and light amplifiers, by sealing them with a sealant such as resin, and is usually mounted at a substrate for use.
Such an electronic part may be mounted at various types of substrates in such a manner that the internal electronic elements are electrically driven. The electronic part is mounted at a substrate by electrically connecting a plurality of leads formed at a surface of the electronic part that are connected to an electrical connector (hereafter referred to as an electronic part connector) to achieve electrical connection of the electronic elements to an electrical connector (hereafter referred to as a substrate connector) such as a wiring formed at a surface of the substrate, in reference to FIGS. 28 and 29.
The following is an explanation of an example of a structure for mounting an electronic part in the prior art, i.e., a semiconductor package having an SVP (surface vertical package) structure at a substrate.
First, in reference to FIG. 28, a schematic structure of the electronic part having the SVP structure is explained. FIG. 28(a) is a front view of an SVP10, whereas FIG. 28(b) presents a transverse cross section of the SVP10.
The SVP10 is formed as a rectangular hexahedron with two large area portions constituting the front and the rear of the SVP10 and four side surface portions that constitute the thickness of the SVP10. An integrated semiconductor element 12 is sealed by a sealant 14 constituted of ceramic or a glass epoxy resin in the SVP10 so that the semiconductor element is protected from an external force or the like. As shown in FIG. 28, a plurality of leads 16 project out from one side surface in the direction of its thickness of the SVP10, which formed as a roughly plate-shaped hexahedron. Every two leads 16 constitutes a pair and in each pair the leads 16 are bent alternately to the left and to the right. It is to be noted that the internal semiconductor element 12 and the individual leads 16 are connected with each other via a wiring (not shown).
FIG. 29 shows a state in which a plurality of SVP10 devices are mounted at a surface of a substrate 20. A plurality of connectors 22 are provided at the surface of the substrate 20, with each of the connectors 22 having a groove 24 for mounting an electronic part 10. In each groove 24, a contact pin 26, which is electrically connected to a substrate connector (not shown) formed at the substrate 20, is provided. When the electronic parts 10 are mounted, the individual electronic parts 10 are inserted in the grooves of the corresponding connectors 22 and electrical connection is achieved by placing the leads 16 and the contact pins 26 in electrical contact with each other.
Thus, by inserting the leads 16 formed at one side surface in the direction of the thickness of the roughly plate-shaped package of the SVP10 at the connector 22 of the substrate 20, the SVP10 can be mounted with the large area portions of the electronic part 10 oriented in the vertical direction.
However, since an electronic part in the prior art is mounted through connection with the wiring at the surface of the substrate via a contact pin, there is a problem in that the path through which an electrical signal is communicated is naturally long. In addition, since an electrical connection is achieved at two locations, i.e., between the leads and the contact pins and between the contact pins and the substrate connector formed at the surface of the substrate, there is a concern that contamination of the contact surfaces may result in increased contact resistance. Thus, problems such as a delay in electrical signals and increased noise are yet to be addressed in the mounting structure of electronic parts in the prior art.